The present invention is more particularly directed towards a support head which allows rotational movement of the optical or video-photographic apparatus about two mutually perpendicular axes.
In the technical field being referred to, there are known support heads which allow rotation of the optical or video-photographic apparatus about a so-called pan axis or a tilt axis or about a level axis.
In one standard configuration for mounting the video-photographic apparatus on the support head, the pan axis is a vertical axis and typically serves to rotate the apparatus by keeping it in the same horizontal plane (useful for horizontally adjusting a framing shot, for example, for panoramic shots), the tilt axis is a horizontal axis which serves to rotate the apparatus by keeping it in a vertical plane which extends through the optical axis of the apparatus (useful for vertically adjusting a framing shot) and the level axis is a horizontal axis which serves to rotate the apparatus by keeping it in a vertical plane which is perpendicular to the optical axis of the apparatus useful for moving from a horizontal position (landscape position) of the apparatus to a vertical position (portrait position).
There are particularly used support heads which are able to rotate at least about two of the three above-described axes.
Those support heads can be provided with locking mechanisms which are separate and independent for each axis of rotation or, conversely, can be provided with a mechanism which allows simultaneous locking/unlocking of the rotation about both axes with a single movement by the user.
An example of a mechanism of that second type which is widely used in the field is described, for example, in U.S. Pat. No. 6,739,559 and briefly comprises a first resiliently contractile collar which is connected to a pin which defines the pan axis, that first collar being open at two adjacent ends, from which there extend attachments which have a semi-cylindrical cross-section and which together define the tilt axis. Therefore, there is mounted, about the two semi-cylindrical attachments of the first collar, a second resiliently contractile collar which is open at the two ends thereof, from which there extend attachments which can be selectively moved together by actuating a clamping member, respectively. The second collar is further provided with attachment means for the video-photographic apparatus and the pin around which the first collar extends can be connected to (or is part of) a support structure, such as a tripod or the like.
With that device, the locking is brought about by acting on the single clamping member, for example, a threaded shaft, which moves together the attachments of the second contractile collar about the two semi-cylindrical attachments of the first collar, which in turn are moved together, clamping the first collar around the pin. In that manner, the second collar clamps around the attachments of the first collar, locking rotation about the tilt axis and the first collar becomes clamped around the pin, locking rotation about the pan axis.
However, the above-described known solution has some disadvantages, one of which is constituted by the non-simultaneous locking about the two axes. In reality, it is found that the locking of the two axes often occurs at quite distinct successive moments of time. It is considered that such a disadvantage is substantially attributable to the dimensional play and the different rigidities of the components of the device and that it could be limited by using specific materials and processing operations which are far more precise with low dimensional tolerances. However, that would involve an increase in costs which would act counter to the very aspect which constitutes the greatest advantage of this technical solution, that is to say, its cost-effectiveness.
Another disadvantage encountered in this type of locking mechanism is the “drift” effect which brings about a slight undesirable rotation of the first and/or second collar during the clamping movement thereof.